Introduction to Brain Tumor Stem Cells

Advances in Brain Metastasis Models

To obtain achievements in addressing the clinical challenges of brain metastasis, we need a clear understanding of its biological mechanisms. Brain metastasis research is challenged by many practical scientific barriers. Depending on the purpose of the study, experimental brain metastasis models in vivo can be used. It is now possible to re-create the architecture and physiology of human organs. Human organoids provide unique opportunities for the study of human disease and complement animal models. The translation of experimental findings to clinical application has several barriers in the development of treatment for brain metastasis. A variety of models have provided significant contributions to the knowledge of brain metastasis pathology and remain pivotal tools for examining novel therapeutic strategies.

Preclinical Solid Tumor Models to Study Novel Therapeutics in Brain Metastases

Metastases are the most common malignancy of the adult central nervous system and are becoming an increasingly troubling problem in oncology largely due to the lack of successful therapeutic options. The limited selection of treatments is a result of the currently poor understanding of the biological mechanisms of metastatic development, which in turn is difficult to achieve because of limited preclinical models that can accurately represent the clinical progression of metastasis. Described in this article are in vitro and in vivo model systems that are used to enhance the understanding of metastasis and to identify new therapies for the treatment of brain metastasis. © 2021 Wiley Periodicals LLC.

Proteins of Wnt signaling pathway in cancer stem cells of human glioblastoma

RATIONALE

Glioblastoma multiforme (GBM) is the most aggressive primary glial brain tumor. The prognosis for GBM patients is not favorable, with the median survival time being 15 months. Its treatment resistance is associated with GBM cell population having cancer stem cells (CSCs). Wnt/β-catenin signaling pathway is a strategically important molecular mechanism, providing proliferation of stem cells of all types. This study compares the expression levels of signaling pathway proteins in CD133(+) CSCs and CD133(-) differentiated glioblastoma cells (DGCs).

MATERIALS AND METHODS

the present study used U-87MG cells of human glioblastoma, the material was tested for mycoplasma contamination. High-performance liquid chromatography (HPLC) mass spectrometry was used for proteome analysis. Biological and molecular functions, signaling pathways and protein-protein interactions were analyzed using free-access databases: PubMed, PANTHER, Gene Ontology, Swiss-Prot and KEGG. Protein-protein interactions (PPIs) were analyzed using the STRING database (version 10).

RESULTS

There were identified 589 proteins with significantly changed expression in CD133+ CSCs, as compared with CD133-DGCs (P<0.05). Bioinformatics analysis allowed to attribute 134 differentially expressed proteins to 16 signaling pathways. A significant increase in expression of eight Wnt signaling pathway proteins (APC, CSNK1E, CSNK1A, CSNK2A2, CSNK2B, CTNNB1, DVL1, RUVBL) was detected, as well as four proteins of the non-canonical Wnt pathway-RHOA, ROCK2, RAC2, DAAM1. Special attention should be paid to β-catenin (CTNNB1) with more than 13.98-fold increase of expression in CSCs and Disheveled-associated activator of morphogenesis 1 (DAAM1) with 6.15-fold higher upregulation level.

CONCLUSION

proteins of Wnt/β-catenin signaling cascade are a prospective target for regulating CSCs activity.

Clinical and Survival Impact of Sex-Determining Region Y-Box 2 in Colorectal Cancer: An Integrated Analysis of the Immunohistochemical Study and Bioinformatics Analysis

Transcription factor sex-determining region Y-box 2 (SOX2) involves in the maintenance of cancer stem cells. However, the role of SOX2 in colorectal cancer (CRC) remains unclear. This study was conducted to investigate the effect of SOX2 on CRC. Studies were searched using electronic databases. The combined odds ratios (ORs) or hazard ratios (HRs: multivariate Cox survival analysis) with their 95% confidence intervals (CIs) were calculated. The Cancer Genome Atlas (TCGA) and GEO datasets were further applied to validate the survival effect. The functional analysis of SOX2 was investigated. In this work, 13 studies including 2337 patients were identified, and validation data were enrolled from TCGA and GEO datasets. SOX2 expression was not significantly related to age, gender, microsatellite instability (MSI) status, clinical stage, histological grade, tumor size, pT-stage, lymph node metastasis, distal metastasis, and cancer-specific survival (CSS) but was correlated with worse overall survival (OS: n = 536 patients) (P < 0.05). Furthermore, TCGA data demonstrated similar results, with no significant correlation between SOX2 and pathological characteristics. Further validation data (OS: n = 1408 and disease-free survival (DFS): n = 1367) showed that SOX2 expression was correlated with worse OS (HR = 1.35, 95% CI: 1.11–1.65, P=0.004) and DFS (HR = 1.30, 95% CI: 1.04–1.62, P=0.02). The functional analyses showed that SOX2 involved in cell-cell junction, focal adhesion, extracellular matrix- (ECM-) receptor interaction, and MAP kinase activity. Our findings suggest that SOX2 expression may be correlated with the worse prognosis of CRC.

Meningioma Tumor Microenvironment

The tumor microenvironment consists of noncancerous cells, such as immune cells and fibroblasts, and the proteins produced by these cells as well as the extracellular matrix components in the environment around a tumor. Tumor influences the behavior of the cells present in the surrounding environment, while the cells in the tumor microenvironment modulate the evolution of the tumor. Little is known about the microenvironment of meningioma, the most common benign intracranial tumor. Here, we review the current knowledge of the tumor microenvironment of meningioma and discusses its importance in meningioma tumorigenesis as well as in the designation of novel therapeutic approaches.

Clinical significance of CD133 and Nestin in astrocytic tumor: The correlation with pathological grade and survival

Background

We aimed to investigate the interaction between CD133 and Nestin and further assessed the correlation of CD133 and Nestin with clinicopathological characteristics and survival in patients with astrocytic tumor.

Methods

Totally 127 patients with astrocytic tumor underwent surgical resection were enrolled. Patients’ age, gender, and World Health Organization (WHO) grade were recorded, and the survival data were extracted from the follow‐up records. The expressions of CD133 and Nestin in astrocytic tumor tissues were analyzed by immunohistochemistry assay. The WHO grade I and II astrocytic tumors were defined as low‐grade astrocytic tumors (LGA), the WHO grade III and IV astrocytic tumors were defined as high‐grade astrocytic tumors (HGA).

Results

There were 79 (62.2%), 34 (26.8%), 14 (11.0%), and 0 (0.0%) patients with CD133 negative, low, moderate, and high expression, respectively; 7 (5.5%), 47 (37.0%), 20 (15.7%), 53 (41.7%) patients with Nestin negative, low, moderate, high expression, respectively. CD133 and Nestin were both correlated with advanced WHO grade but not with age or gender, and positive correlation was observed between CD133 and Nestin. For survival, both CD133 and Nestin were correlated with unfavorable overall survival (OS), and further analysis illustrated that Nestin but not CD133 independently predicted poor OS. Subgroup analysis also revealed that Nestin but not CD133 negatively associated with shorter OS in LGA patients, while both CD133 and Nestin were correlated with poor OS in HGA patients.

Conclusion

CD133 and Nestin present as potential biomarkers for advanced pathological grade and poor survival in patients with astrocytic tumor.